(declare-fun a () String)
(declare-fun b () String)
(assert (str.in_re (str.++ (ite (str.in_re b (re.* (re.range "a" "u"))) a "") b) (re.++ (re.range "a" "u") (re.diff (str.to_re "") (str.to_re (ite (str.in_re b (re.* (re.range "a" "u"))) "" b))))))
(assert (str.<= b "a"))
(check-sat)
